• Acta Photonica Sinica
  • Vol. 52, Issue 11, 1122002 (2023)
Yang HUANG*, Chao ZHANG, Zhuwei ZHANG, Shengjie ZHANG, and Chengguang CUI
Author Affiliations
  • Beijing Institute of Space Mechanics & Electricity,Beijing 100094,China
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    DOI: 10.3788/gzxb20235211.1122002 Cite this Article
    Yang HUANG, Chao ZHANG, Zhuwei ZHANG, Shengjie ZHANG, Chengguang CUI. Design and Verification of Automatic Alignment System for Batch Space Refractive Lenses[J]. Acta Photonica Sinica, 2023, 52(11): 1122002 Copy Citation Text show less

    Abstract

    In order to obtain wide-range and high-precision remote sensing information, aerospace powers such as China, the United States, and many other European countries have adopted large-scale, multi orbit, and global coverage satellite deployment methods, and the space cameras are also developing in batches. Compared to traditional remote sensing cameras that only require some traditional imaging performance indicators, batch space cameras increase the requirements for shorter manufacturing cycles and higher image quality uniformity between batches. Due to the characteristics of large field of view, small size, and low cost, refractive lenses have been widely used in batch space cameras. At present, the precision centering error method is mainly used for the adjustment of space refractive lenses at home and abroad. The adjustment process is highly dependent on manual skills and experience. In addition, due to the random deviations of batch materials, lens processing accuracy, lenses adjustment tolerance and other factors, it is difficult to achieve high image quality uniformity of batch lenses while ensuring short adjustment cycle. Therefore, it is necessary to improve the assembly efficiency and quality uniformity of batch lenses by introducing more practical automatic alignment system.With the construction idea of“structural integration, adjustment automation, detection online and correction autonomy”, an automatic lenses alignment system with functions of automatic adjustment, online detection, automatic analysis and correction of wavefront aberrations was developed. Firstly, an automatic lens adjustment method was designed based on the centering error measurement. The measurement values of lens mis-adjustment were converted to the linear movement values of the adjustment devices by coordinate projection, and the automatic adjustment was realized by the combined movements of the adjustment devices driven by the motor. Then, according to the automatic adjustment mode, the lenses structure was designed, and the stability of structural mechanics was analyzed by finite element model. Finally, an integrated platform for lenses adjustment and measurement was built, and a wavefront aberrations correction module was designed. According to the results of system wavefront aberrations measurement, the lenses degree of freedom adjustments were analyzed automatically, and the positions of the lenses were adjusted by driving the adjustment devices to compensate the image quality. The high uniformity of image quality between batches was guaranteed by correcting residual wavefront aberrations equally.In the experiment, 20 refractive lenses were aligned by this automatic alignment system. Taking the first lenses alignment as an example, firstly, during the automatic adjustment process, the lens mis-adjustment values could be controlled within tolerance by two position adjustments. Then, through online detection of lenses wavefront aberrations and MTF, the degrees of freedom adjustments for lenses were calculated automatically. Finally, by automatically correcting residual wavefront aberrations, the wavefront aberrations of the lenses in 5 fields of view were evenly improved. The average MTF (@33 lp/mm) at the lenses edge fields of view was increased from 0.616 to 0.665, and the maximum deviation of MTF was decreased from 0.086 to 0.003, which laid the foundation for the image quality uniformity in the corresponding field of view between batches. The results of 20 lenses alignment and measurement show that the use of automatic alignment system can significantly reduce manual operations, and the alignment cycle is reduced to 3 days per set. By automatic adjustment, the accuracy of lenses tilt, decenter and distance is respectively better than 10″, 5 μm and 5 μm. Furthermore, after automatic correction of wavefront aberrations, the maximum deviation of MTF in the corresponding field of view between batches is 0.026. 20 lenses alignment results meet the requirements.In this study, an automatic alignment system for batch space refractive lenses was developed, which solved the problem that traditional methods can't meet the requirements of short manufacturing cycles and high image quality uniformity between batches, and realized automatic closed-loop control of lens adjustment, image quality detection, degree of freedom adjustment analysis and wavefront aberration correction. It provides an efficient and automatic development way for the batch space refractive lenses. The principles and methods can be extended to the alignment of reflective optical system, and have important reference significance for the design and development of other similar products.
    Yang HUANG, Chao ZHANG, Zhuwei ZHANG, Shengjie ZHANG, Chengguang CUI. Design and Verification of Automatic Alignment System for Batch Space Refractive Lenses[J]. Acta Photonica Sinica, 2023, 52(11): 1122002
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